1. Field of the Invention
The present invention relates to a cleaning method and a cleaning device, and more specifically to a cleaning method and a cleaning device which can remove foreign materials deposited on a substrate after removal of photoresist by plasma processing.
2. Background Technology
Conventionally, when separating resist in production of semiconductors or liquid-crystal display units, generally sulfuric acid and hydrogen peroxide are mixed with each other in the state of respective raw liquids under a high temperature in a range from 100 to 150.degree. C. Or, in a case where the solution above has strong acidity and can not be used because of the bad effects over the substrate or other portions, an organic solvent with high concentration is used under a high temperature to remove the foreign materials as described above. Also in semiconductor production in recent years, a degree of integration to be realized has been becoming increasingly higher and higher, so that ion injection or reactive ion etching is required using photoresist as a mask, but in this type of processing a large quantity of ions is irradiated onto a surface of photoresist, and the photoresist material itself is bridged and cured, so that it is difficult to remove the foreign materials as described above only by means of wet cleaning in which a mixed solution of sulfuric acid and hydrogen peroxide or a high concentration organic solvent is used, and for this reason, after the cured photoresist section is burnt and removed by employing the plasma processing with oxygen plasma, and then remaining photoresist is removed with a chemical agent.
In the plasma processing, however, there are such defects as that foreign materials such as metal or fine particles included in photoresist remain after processing on the substrate, that, in ion injection, a large quantity (10.sup.15 /cm.sup.2 or more) of such elements as phosphor or boron is irradiated, the photoresist material itself is bridged and cured, and can not completely be removed after the processing, and photoresist remains as a foreign material on the substrate, or that, in reactive etching by using a fluorocarbon (CF)-based material, a CF-based deposited material layer is formed on the photoresist and the CF-based deposited material remains as a foreign material after the plasma processing, and there is the problem that the foreign materials as described above can not completely be removed by using sulfuric acid and hydrogen peroxide, or an organic solvent.
Further, in the method of a mixed solution of sulfuric acid and hydrogen peroxide, the processing is executed using a high density solution under a high temperature, so that use of the cleaning liquid or transfer of silicon wafer is rather poor in its operability, and further hydrogen peroxide in the cleaning liquid is decomposed because of the high density and high temperature employed in the processing, so that management of the solution is very complicated, and in addition, a large quantity of vapor of chemicals or water is generated, and a large volume of clean air is required and a scrubber is required to remove vapor of chemicals from the exhaust air, which results in high power cost as well as in high device cost, and moreover high cost is disadvantageously required to process wasted liquid of the sulfuric acid.
Also the method of using an organic solvent is carried out under a high temperature and the operability is very poor, and further management of the processing liquids is difficult and it is substantially impossible to recover or recycle the processing liquids.